24 research outputs found
Beyond the perfect fluid hypothesis for dark energy equation of state
Abandoning the perfect fluid hypothesis, we investigate here the possibility
that the dark energy equation of state (EoS) is a nonlinear function of the
energy density . To this aim, we consider four different EoS describing
classical fluids near thermodynamical critical points and discuss the main
features of cosmological models made out of dust matter and a dark energy term
with the given EoS. Each model is tested against the data on the dimensionless
coordinate distance to Type Ia Supernovae and radio galaxies, the shift and the
acoustic peak parameters and the positions of the first three peaks in the
anisotropy spectrum of the comic microwave background radation. We propose a
possible interpretation of each model in the framework of scalar field
quintessence determining the shape of the self interaction potential
that gives rise to each one of the considered thermodynamical EoS. As a general
result, we demonstrate that replacing the perfect fluid EoS with more generar
expressions gives both the possibility of successfully solving the problem of
cosmic acceleration escaping the resort to phantom models.Comment: 15 pages, 4 figures, accepted for publication on Physical Review
Sur les chaleurs spécifiques de l'acide carbonique et de l'isopentane - (Réponse aux remarques faites à ce sujet par M. E. Mathias)
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